1. Field of the Invention
The present invention relates to a thin film magnetic head integrated structure used for manufacturing a thin film magnetic head having at least an inductive magnetic transducer for writing, and a method of manufacturing the thin film magnetic head integrated structure, as well as a method of manufacturing a thin film magnetic head using the thin film magnetic head integrated structure.
2. Description of the Related Art
Recently, an improvement in the surface recording density of a magnetic recording medium (hereinafter referred to simply as a “recording medium”), such as a hard disk, requires an improvement in the performance of a thin film magnetic head mounted on a magnetic recording device such as a hard disk drive (HDD). As a recording system of the thin film magnetic head, there are known a longitudinal recording system that sets the direction of a signal magnetic field to the inplane direction (the longitudinal direction) of a recording medium, and a perpendicular recording system that sets the direction of a signal magnetic field to a direction orthogonal to a surface of a recording medium. At the present, the longitudinal recording system is widely used. However, in consideration of a market trend along with an improvement in the surface recording density of a recording medium, the perpendicular recording system seems more favorable than the longitudinal recording system in the future. This is because the perpendicular recording system has the advantage that a high linear recording density can be ensured and a recording medium after recording is less susceptible to the influence of thermal fluctuation.
A thin film magnetic head of perpendicular recording system includes mainly a thin film coil that generates a magnetic flux, and a magnetic pole layer that extends from an air bearing surface to the rear and performs a write process by emitting a magnetic flux generated in the thin film coil toward a recording medium. The magnetic pole layer includes a track-width-defining part of a width (a uniform width) that defines a write track width. The height of the track-width-defining part, namely the size from the front end (the edge exposed on the air bearing surface) to the rear end (a so-called flare point), is a neck height that is an important factor contributing to the write performance of the thin film magnetic head. In the thin film magnetic head of perpendicular recording system, when a magnetic flux for writing is generated by energization of the thin film coil, the magnetic flux is emitted from the tip of the track-width-defining part in the magnetic pole layer, so that a magnetic field (a vertical magnetic field) for writing is generated and the surface of the recording medium is magnetized by the vertical magnetic field. This enables information to be written magnetically on the recording medium.
As a thin film magnetic head of this type, there has recently been spread a composite-type thin film magnetic head (hereinafter referred to simply as a “composite thin film magnetic head), which functions to perform not only a write process with respect to a recording medium (write magnetically information on the recording medium), but also a read process with respect to the recording medium (read magnetically the information written in the recording medium). For example, the composite thin film magnetic head is provided with both of a write head core that performs the write process of the above-mentioned perpendicular recording system, and a read head core that performs the read process by using magneto-resistive effect (MR). The read head core contains an MR element extending from an air bearing surface to the rear, as the executing body of the read process. The height of the MR element, namely the size from the front end of the MR element (the edge exposed on the air bearing surface) to the rear end (the edge far from the air bearing surface), is an MR height that is an important factor contributing to the read performance of the thin film magnetic head.
For the purpose of a batch manufacturing of a plurality of composite thin film magnetic heads, the composite thin film magnetic heads are generally manufactured by using a thin film magnetic head integrated structure that a plurality of thin film magnetic head precursors are disposed on a wafer. The thin film magnetic head precursors are preformed bodies for forming thin film magnetic heads, and arranged in a plurality of rows on the wafer. In particular, the thin film magnetic head precursors have the same configuration as the completed composite thin film magnetic head including the read head core and the write head core, except for the absence of an air bearing surface.
In the manufacturing process of the composite thin film magnetic head, thin film magnetic heads are completed by the steps of: forming a plurality of thin film magnetic head bars by cutting the thin film magnetic head integrated structure along the direction of arrangement of the thin film magnetic head precursors; and forming an air bearing surface by grinding one end surface of each of the thin film magnetic head bars (a cut surface formed after cutting the thin film magnetic head integrated structure) until the after-polishing sizes of a read head core and a write head core become their respective predetermined sizes, more specifically, until the MR height of the read head core has a predetermined size and the neck height of the write head core has a predetermined size. Thereafter, the thin film magnetic head bars with the air bearing surface formed thereon are cut per thin film magnetic head, resulting in a plurality of magnetic head sliders.
With regard to the above-mentioned manufacturing process of the composite thin film magnetic heads, several techniques have been proposed to control the progress of a grinding process in the grinding step for forming the air bearing surface. For example, there is known a technique of forming, in the step of forming thin film magnetic head precursors, dummy sensors for monitoring within the thin film magnetic head precursors, and then performing the grinding process while measuring the MR height on the dummy sensors (refer to, for example, Japanese Unexamined Patent Publication No. 11-000863). There is also known the technique of performing the grinding process while measuring the electrical resistance values of MR elements in a plurality of thin film magnetic head precursors and calculating an average value of the electrical resistance values, instead of measuring the MR height (refer to, for example, Japanese Unexamined Patent Publication No. 02-095572). Both of the above techniques are capable of controlling the amount of grinding so that the MR height has a predetermined size.